This invention relates generally to solid material comminution apparatus and more particularly to those having automatic control of comminutor drive.
Apparatus, such as a grinder-mixer, is used to mix livestock feed rations. One of the major ingredients in such feed is hay. The hay is fed to a grinder on a material infeed device commonly known as a feed table. The feed table and the grinder ultimately derive power from a common prime power source usually supplied by an agricultural tractor connected to the grinder-mixer via a power takeoff (PTO) shaft. An associated power source usually operates off the prime source for supplying motive power to the feed table. This associated power may be termed either mechanical or hydraulic.
Mechanical feed table drive is limited to having a fixed speed which must be manually adjusted to cope with varying bale density. For example, an unusually dense or wet bale can cause an overload on the grinder causing the prime power source to lug down and sometimes stall. If the feed table speed is not slowed or stopped, the lug down becomes more severe. Manual speed adjustment requires operator attention and since the operator is busy supplying bales to the feed table, he cannot always manually adjust feed table speed in time to avoid a stall.
In hydraulic systems, motive power is supplied to the feed table by a hydraulically operated motor. A push-pull type valve has been used to be automatically actuated to cut-off feed table motive power when a lug down occurs. However, this push-pull type valve has the limitations of being expensive and complicated.
The foregoing illustrates limitations of the known prior art. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations as set forth above.